A street vendor grills corn as Egyptian soldiers stand guard at the Presidential Palace on Tuesday, December 18, in Cairo. Protesters opposed to President Mohamed Morsy's first round of voting in the constitutional referendum gather during continuing demonstrations.
Protesters chant slogans during a demonstration at the Presidential Palace on December 18 in Cairo.
An Egyptian woman types on her laptop before the start of a demonstration opposing President Mohamed Morsy on December 18 in Cairo.
People make their way through a market place on Monday, December 17, in Cairo.
A supporter of Egypt's President Mohamed Morsy and the Muslim Brotherhood holds Quran as he shouts during a demonstration in Cairo on Friday, December 14.
Women pray during a demonstration in support of President Mohamed Morsy in Cairo on December 14.
Egyptian army tanks are deployed outside the presidential palace in Cairo on Thursday, December 13. Egypt's crisis showed no sign of easing as the army delayed unity talks meant to ease political divisions and the opposition set near-impossible demands for taking part in a looming constitutional referendum.
Girls walk with Egypt's national flag draped over their backs to a rally for supporters of President Mohamed Morsy in Cairo on Tuesday, December 11.
Protesters on December 11 attempt to bring down cement walls that security forces placed around the presidential palace in Cairo.
Security forces stand guard in front of the presidential palace in Cairo on December 11.
Protesters opposed to Egypt's president demonstrate on top of a barricade erected by the Egyptian army to protect the presidential palace in Cairo on December 11.
A young protester climbs atop a barricade erected by the Egyptian army on December 11. There were no incidents of violence and soldiers held the line as a couple of hundred protesters pressed up against waist-high crowd barriers.
Protesters remove part of a metal barrier protecting the presidential palace on December 11.
Egyptian army troops stand guard in front of a metal barricade on December 11.
An Egyptian army soldier patrols outside the Egyptian presidential palace on Monday, December 10, in Cairo. The Egyptian political crisis erupted last month when President Mohamed Morsy issued an edict allowing himself to run the country unchecked until the drafting of a new constitution.
Members of the Egyptian opposition gather for a protest outside the presidential palace on Sunday, December 9, in Cairo. The palace has been the scene of violent clashes pitting thousands of protesters -- for and against Morsy.
Guy Fawkes masks are displayed by a street vendor in front of the Egyptian presidential palace in Cairo on December 9. The masks depict Fawkes, a rebel executed in England's Gunpowder Plot seeking to blow up the House of Lords in the early 1600s.
Egyptian army engineers and soldiers build a third line of concrete blocks outside of the Egyptian presidential palace in Cairo in preparation for more protests on December 9.
An Egyptian protester sweeps the street near army tanks deployed outside the presidential palace in Cairo on December 8, after continued protests overnight.
A sticker depicting Egyptian President Mohamed Morsy reads "leave" on the ground near the presidential palace on December 8.
Egyptian soldiers take position on a road leading to the presidential palace on December 8.
A protester tries to climb over a barbed-wire fence as Egyptian soldiers stand guard during a demonstration near the presidential palace in Cairo on Friday, December 7.
Supporters of Egyptian President Mohamed Morsy and members of the Muslim Brotherhood shout during the funerals of fellow Morsy supporters at Al-Azhar mosque in Cairo on December 7.
Protesters angry over Morsy's decisions giving himself unchecked powers surround the Muslim Brotherhood's headquarters in Cairo after starting a fire inside the compound on Thursday, December 6.
Riot police form a line as anti-Morsy protesters surge around the Muslim Brotherhood's headquarters in Cairo on December 6.
An anti-Morsy protester shouts during a march to the presidential palace in Cairo, Egypt, on December 6.
Protesters are blocked from approaching the the presidential palace by the Egyptian army on December 6 in Cairo.
Egyptian soldiers stand outside the presidential palace in Cairo after setting up barbed wire barricades on December 6.
Supporters of Morsy clash with anti-Morsy protesters outside the Egyptian presidential palace on Wednesday, December 5, in Cairo.
Members of the Muslim Brotherhood and Morsy supporters destroy tents of anti-Morsy protesters outside the presidential palace on December 5.
Morsy supporters carry an injured man to safety during clashes with anti-Morsy demonstrators on a road leading to the Egyptian presidential palace on December 5.
Members of the Muslim Brotherhood and supporters of Morsy clash with anti-Morsy demonstrators on a road leading to the Egyptian presidential palace on December 5.
Egyptian riot police stand behind barbwire as thousands of Egyptian demonstrators march to the presidential palace in Cairo, Egypt, on Tuesday, December 4.
Tens of thousands of demonstrators encircled the presidential palace in Cairo after riot police failed to keep them at bay with tear gas on December 4.
An Egyptian woman waves a national flag as demonstrators march to the presidential palace in Cairo on December 4.
A Morsy supporter waves a flag outside the Supreme Constitutional Court as hundreds of supporters of the president protest on Sunday, December 2, in Cairo, forcing judges to postpone a hearing on a constitutional panel at the heart of a deepening political crisis.
Supporters of Morsy pray outside the Supreme Constitutional Court on December 2.
A man kisses a portrait of Morsy during a gathering of thousands of Islamists in front of Cairo University on Saturday, December 1.
Thousands pray during a rally in support of Morsy in front of Cairo University on December 1.
An Egyptian man delivers a speech as protesters gather in Cairo's Tahrir Square on Friday, November 30.
A man shouts as protesters gather in Tahrir Square on November 30.
A man holds a copy of the Quran and a cross in Tahrir Square on November 30.
Protesters run from Egyptian riot police during clashes near Cairo's Tahrir Square on Wednesday, November 28.
A protester carries a rock during clashes with police on Wednesday.
Egyptians carry a giant national flag as tens of thousands take part in a mass rally in Cairo on Tuesday, November 27, against a decree by President Mohamed Morsy granting himself broad powers.
An Egyptian protester holds up a Quran and a figure of Christ on the cross during Tuesday's demonstration.
Protesters continue to rally in Tahrir Square on Tuesday.
An Egyptian protester attempts to throw back a tear gas canister on Tuesday during clashes with riot police in Omar Makram Street, off Tahrir Square.
Activists in Cairo's Tahrir Square on Monday, November 26, carry the coffin of Gaber Salah, an activist who died overnight after he was critically injured in clashes in Cairo. Salah, a member of the April 6 movement known by his nickname "Jika," was injured last week during confrontations between police and protesters on Cairo's Mohammed Mahmud street.
Thousands of activists attend the funeral of Gaber Salah on Monday.
Protesters clash with Egyptian police at Simon Bolivar Square on Sunday, November 25, in Cairo. Egypt's powerful Muslim Brotherhood called nationwide demonstrations in support of Islamist President Mohamed Morsy in his showdown with the judges over the path to a new constitution.
Egyptian protesters hurl stones at police at Tahrir Square on Sunday.
Protesters gather at sit-in tents in Tahrir Square on Sunday.
Egyptian President Mohamed Morsy waves to supporters in front of the presidential palace in Cairo on Friday, November 23. Thousands of ecstatic supporters gathered outside the presidential palace to defend their leader against accusations from rival protesters that he has become a dictator.
Morsy supporters gather outside the presidential palace in Cairo on Friday. Morsy insisted that Egypt was on the path to "freedom and democracy," as protesters held rival rallies over sweeping powers he assumed that further polarized the country's political forces.
Protesters demonstrating against Morsy run from tear gas fired by Egyptian riot police during clashes in Cairo's Tahrir Square on Friday.
Egyptian protesters throw rocks toward riot police on Friday
Egyptian supporters and opponents of Morsy clash in the coastal city of Alexandria on Friday.
A man throws a rock during clashes in Alexandria on Friday.
Thousands of demonstrators march through the streets of Cairo to protest against Morsy on Friday.
Clashes rocked the coastal city of Alexandria on Friday.
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
Egyptians protest over presidential powers
STORY HIGHLIGHTS
- Morsy chief of staff says president's address will contain important information
- The announcement comes after more than 200 people were hurt Wednesday
- Masked men set fire to Muslim Brotherhood offices in three cities
- Opposition leaders say they are prepared to start talks with Morsy if he withdraws his edict
Cairo (CNN) -- As protesters battled supporters of Egyptian President Mohamed Morsy outside his palace, his chief of staff announced Thursday that the president would address the nation later in the day.
The chief of staff, Refaa El-Tahtawy, said the speech would include important news but did not specify what that might be.
The announcement came hours after demonstrations erupted into violence Wednesday night over Morsy's assumption of sweeping powers last month.
Three of Morsy's advisers resigned Wednesday in protest of his edict, while demonstrators set fire to offices of the Muslim Brotherhood and its political arm, the Freedom and Justice Party, in three cities.
The unrest comes as Egypt lurches toward a scheduled December 15 referendum on a new constitution. Days of largely peaceful protests in Tahrir Square had preceded Wednesday's violence.
But that all changed Wednesday. After Morsy supporters chased protesters from the grounds, pro- and anti-Morsy demonstrators threw rocks, fireworks and Molotov cocktails at each other.
Morsy spokesman: He wants democracy
Rocks fly during clashes in Cairo
Egypt's media blackout
Egypt's prime minister on turmoil
Pro-Morsy supporters turn out in force
Late in the day, a spokesman for the Muslim Brotherhood called on protesters to withdraw from the area of the palace "and not to protest there again due to its significant symbolic position as the president's office."
The Health Ministry reported four were killed and 271 were injured; state media reported earlier in the night that no one was killed.
Dr. Mohamed Sultan, a spokesman for the ministry, said the injuries ranged from bruises to cuts, burns and fractures.
More marches were promised for Thursday, said Rami Shath, a member of the Revolutionary Alliance and the Free Egyptian Party.
"We hold opposition figures, namely Sabbahi & ElBaradei, fully responsible for escalation of violence & inciting their supporters," said the Muslim Brotherhood in a tweet, referring to opposition leaders Hamdeen Sabbahi and Mohamed ElBaradei.
Morsy, Egypt's first freely elected leader, was a Muslim Brotherhood leader before winning office in June, when he resigned from the movement and the Freedom and Justice Party to represent all Egyptians, he said. Demonstrators were protesting his recent edict granting himself sweeping powers and the proposed constitution -- drafted by an Islamist-dominated council -- that they fear will give him even more power.
"This is not what we asked for," one protester said. "It's a complete dictatorship."
Other protesters vowed to remain in the streets until Morsy is forced to leave office. "He's not our president anymore," another protester said.
The three advisers who announced their resignations said they had done so after failing to persuade Morsy to reverse his November 23 decree.
"He has rejected all our suggestions and initiatives that may have avoided the cycle of violence we are witnessing today," Ayman al-Sayad, Seif Abdel Fattah, and Mohammed Esmat said in a joint statement.
But the powerful Muslim Brotherhood called the protesters "thugs" who were trying to overthrow the president.
"By the grace of God, the Egyptian people will be able to protect this legitimacy, its constitution and its institutions," the group said on its Facebook page.
Ahmed Sobea, a spokesman of the Freedom and Justice Party, said the party's offices in the northeastern cities of Suez and Ismailia had been ransacked and torched by masked, armed men on Wednesday night. The offices were empty when the attacks occurred, Sobea said.
State-run Nile TV broadcast pictures of the Ismaila office on fire and reported that other masked men had burned the Muslim Brotherhood headquarters in the northeastern city of Zagazig.
Opposition leaders are prepared to open talks with Morsy if he withdraws his edict and delays the referendum, said ElBaradei, leader of the liberal Constitution Party and a Nobel Peace Prize laureate. But Vice President Mahmoud Mekki said the referendum will be held as planned.
"Saying the referendum will be held on time is not being stubborn," Mekki said. "The president has backtracked from decisions before; he's not a stubborn character."
Morsy's decree placed his decisions out of the reach of courts until a new constitution is approved. He said the move was designed to protect the spirit of the popular 2011 uprising that drove former strongman Hosni Mubarak from power.
Critics call it a power grab.
Egyptian judges and media outlets as well as liberal political groups have protested Morsy's decree and the proposed constitution, saying it goes against the goals of the revolution.
How the struggle plays out could have repercussions across the Middle East and North Africa, regions already wracked by upheaval. In nearby Gaza and Israel, tensions remain high after last month's fighting. In Syria, a civil war has raged since March 2011.
Wednesday's violence followed clashes Tuesday outside the palace, which has become the focus of protests by Egypt's liberal opposition.
On Tuesday night, police fired tear gas after anti-Morsy protesters broke through barbed wire around the palace and hurled chairs and rocks at retreating officers. After the initial clashes, police withdrew behind fences and the demonstration was peaceful for several hours.
Yassir Ali, a spokesman for the presidential office and the vice president, told reporters Wednesday that the presidential office had ordered the security forces at the palace "to protect the protesters and keep them safe."
"The orders to the security forces were not to confront (them), (but) to preserve the lives of the protesters and to prevent any clashes between the security forces and the protesters," Ali said.
CNN's Reza Sayah and Journalists Mohamed Fadel Fahmy and Sarah Sirgany reported from Cairo, CNN's Michael Pearson, Joe Sterling, Saad Abedine and Yousuf Basil reported from Atlanta, and Sarah Brown and Laura Smith-Spark reported from London.